1) a^2 — 10a+25=(a — 5) ^2 2) 25 — a^2=(5+a) (a — 5) 3) (b — 1) (a — 5)=- (1 — b) (a — 5) 4) (a — 1) (2a — 5)=2a^2+2a — 5

1) a^2 — 10a+25=(a — 5) ^2 (a — 5) ^2=a^2-10a+25 a^2-10a+25=a^2-10a+25 a^2-10a+25-a^2+10a-25=0 0=0 2) 25 — a^2=(5+a) (a — 5) 3) (b — 1) (a — 5)=- (1 — b) (a — 5) 25-a^2-5a+a^2+25a-5a=0 (b — 1) (a — 5)=(b+1) (a — 5) 15a+25=0 ba-a-5b-ba-a+5b+5=0 15a=-25 2a+5=0 a=-25/-15 2a=-5 a=5/3 a=-5/-2 a=2,5